ASUNCION, Paraguay - Ten prisoners in a jail in Paraguay have been killed after a riot broke out on Sunday.

Half of those killed are believed to have been beheaded, while three were burnt to death.

The riot is believed to have been an offshoot to a vicious brawl between two warring factions in the prison, which is located at San Pedro de Ycuamandiyu, the capital of San Pedro Department, situated around 400 kilometres northeast of the Paraguayan capital Asuncion.

The riot is understood to have broken out at about midday on Sunday and continued through to about 3:00pm, at which time it was brought under control.

The "confrontation" was between "two feared criminal organizations" the Ministro del Interior (Minister of the Interior), Juan Ernesto Villamayor said Sunday.

"All of the dead belong to the narco groups," he said.

One of the factions is believed to consist of drug dealers from Sao Paulo in Brazil known as Primer Comando da Capital, while the other is believed to comprise drug traffickers from both Brazil and Paraguay, and is known within the prison as the Rotela criminal group.

Prison and local law enforcement officials have launched an investigation into the riot and the deaths.